Spectrometry device, image forming apparatus, and spectrometry method

Abstract

A printer includes a spectroscope and a carriage moving unit. The spectroscope includes a wavelength-selective interference filter on which light from a measurement target is incident, and the carriage moving unit moves the spectroscope in an X direction with respect to the measurement target. If the measurement target is a color patch, the spectroscope performs spectrometry by changing a wavelength of light passing through the wavelength-selective interference filter in a first period during which the spectroscope is moved in the X direction, and passes light of an initial wavelength through the wavelength-selective interference filter at a start of measurement and at an end of measurement in the first period. A first output value that is a measured value from the spectrometry at the start of measurement is compared with a second output value that is a measured value from the spectrometry at the end of measurement.

What is claimed is: 
     
       1. A spectrometry device comprising:
 a spectroscope that measures a measured value of light; and 
 a moving mechanism that moves the spectroscope relative to a measured target, 
 wherein the spectroscope is configured to measure:
 a first measured value of light at a first wavelength at a first time; 
 a second measured value of light at a second wavelength at a second time; and 
 a third measured value of light at the first wavelength at a third time, and 
 
 wherein the first measured value is compared with the third measured value. 
 
     
     
       2. A spectrometry device comprising:
 a spectroscope that includes a wavelength-selective interference filter on which light from a measurement target is incident, wherein the spectroscope is configured perform spectrometry on the measurement target; and 
 a moving mechanism that moves the spectroscope relative to the measurement target in one direction, wherein: 
 when the measurement target is a color patch, the spectroscope changes a wavelength of light passed by the wavelength-selective interference filter in a first period during which the spectroscope is relatively moved in the one direction, the wavelength-selective interference filter passes light of a first wavelength at a start of measurement and at an end of measurement in the first period, and a first measured value that is a measured value from the spectrometry at the start of measurement is compared with a second measured value that is a measured value from the spectrometry at the end of measurement. 
 
     
     
       3. The spectrometry device according to  claim 1 , wherein:
 the difference between the first measured value and the second measured value is compared with a first threshold to determine if the difference is less than or equal to the first threshold. 
 
     
     
       4. The spectrometry device according to  claim 2 , wherein:
 the spectroscope includes a light receiver that receives light emitted from the wavelength-selective interference filter, and 
 the first measured value is compared with the second measured value by using an output value from the light receiver. 
 
     
     
       5. The spectrometry device according to  claim 2 , further comprising:
 a control unit that controls the spectroscope and the moving mechanism. 
 
     
     
       6. The spectrometry device according to  claim 5 , wherein:
 the control unit includes a filter controller that changes a wavelength of light passing through the wavelength-selective interference filter. 
 
     
     
       7. The spectrometry device according to  claim 2 , wherein:
 the spectroscope performs spectrometry on a plurality of the color patches arranged in the one direction, the color patch in which the measured value is greater than or equal to a second threshold is selected, and the first measured value and the second measured value of the selected color patch are compared with each other. 
 
     
     
       8. The spectrometry device according to  claim 2 , wherein:
 a first position is a position of the spectroscope at the time of measuring the first measured value, 
 a second position is a position of the spectroscope at the time of measuring the second measured value, 
 a difference between the first measured value and the second measured value is compared to a first threshold, and 
 when the difference between the first measured value and the second measured value is greater than the first threshold, a direction in which the first position and the second position are shifted from the first position and the second position at the time of the spectrometry performed within the region of the color patch is detected. 
 
     
     
       9. The spectrometry device according to  claim 8 , wherein:
 the direction of the shift is detected based on the first measured value, the second measured value, a third measured value, and a fourth measured value, 
 the third measured value is a measured value before the first period at the time of performing the spectrometry with light of the first wavelength by relatively moving the spectroscope in the one direction, and 
 the fourth measured value is a measured value after the first period at the time of performing the spectrometry with light of the first wavelength by relatively moving the spectroscope in the one direction. 
 
     
     
       10. The spectrometry device according to  claim 8 , wherein:
 the direction of the shift is detected based on a reflectance of a color around the color patch with respect to the first wavelength, the first measured value, and the second measured value. 
 
     
     
       11. The spectrometry device according to  claim 2 , wherein:
 the difference between the first measured value and the second measured value is compared to a first threshold, and 
 when the difference between the first measured value and the second measured value is greater than the first threshold, an amount of shifting by which a first position and a second position are shifted from the first position and the second position at the time of the spectrometry performed within the region of the color patch is calculated, wherein the first position is a position of the spectroscope at the time of measuring the first measured value, and the second position is a position of the spectroscope at the time of measuring the second measured value. 
 
     
     
       12. The spectrometry device according to  claim 11 , wherein:
 the amount of shifting is calculated based on the first measured value and the second measured value with respect to two or more of the color patches continuously arranged. 
 
     
     
       13. The spectrometry device according to  claim 2 , wherein:
 the moving mechanism moves the spectroscope in the one direction at a uniform speed. 
 
     
     
       14. An image forming apparatus comprising:
 the spectrometry device according to  claim 1 ; and 
 an image forming unit that forms an image on an image formation target. 
 
     
     
       15. An image forming apparatus comprising:
 the spectrometry device according to  claim 2 ; and 
 an image forming unit that forms an image on an image formation target. 
 
     
     
       16. An image forming apparatus comprising:
 the spectrometry device according to  claim 3 ; and 
 an image forming unit that forms an image on an image formation target. 
 
     
     
       17. An image forming apparatus comprising:
 the spectrometry device according to  claim 4 ; and 
 an image forming unit that forms an image on an image formation target. 
 
     
     
       18. An image forming apparatus comprising:
 the spectrometry device according to  claim 5 ; and 
 an image forming unit that forms an image on an image formation target. 
 
     
     
       19. A spectrometry method comprising:
 providing a spectroscope that is configured to move relative to a measurement target; 
 measuring a first measured value of light at a first wavelength at a first time using the spectroscope; 
 measuring a second measured value of light at a second wavelength at a second time using the spectroscope; 
 measuring a third measured value of light at the first wavelength at a third time using the spectroscope; and 
 comparing the first measured value with the third measured value. 
 
     
     
       20. A spectrometry method that performs spectrometry on a color patch as a measurement target by using a spectrometry device that includes a spectroscope, the spectroscope includes a wavelength-selective interference filter on which light from the measurement target is incident and a moving mechanism that moves the spectroscope relative to the measurement target in one direction, the method comprising:
 relatively moving the spectroscope in the one direction; 
 performing spectrometry by changing a wavelength of light passing through the wavelength-selective interference filter in a first period during which the spectroscope is relatively moved; 
 passing light of a first wavelength through the wavelength-selective interference filter at a start of measurement and at an end of measurement in the first period; and 
 comparing a first measured value that is a measured value from the spectrometry at the start of measurement with a second measured value that is a measured value from the spectrometry at the end of measurement.